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Electrical

Parallel Resistance Calculator

Find equivalent resistance of two parallel resistors.

Ideal component relationshipsUnits and assumptions explained below
Circuit workbench
Circuit workbench

Keep RMS, peak and DC values distinct.

See the method

Enter circuit values

Runs on your device

Your circuit result

Your result

Let’s calculate.

Use the Calculate button to see your result.

Review the method below for assumptions and conventions.

How to use this tool

  1. Enter first resistance, second resistance.
  2. Select Calculate to view the result.
  3. Check the method and assumptions below before using the result.

Input reference and sample values

Use the units and choices shown for each field. Sample values are provided for practice, not as recommendations.

InputFormat and unitsSample
First resistanceNumeric value. Unit: Ω. Must be greater than zero.100
Second resistanceNumeric value. Unit: Ω. Must be greater than zero.200

Result for these sample inputs

66.6666667 Ω

Select Try the example in the form to load these values and calculate them again. This replaces the current form inputs. Compare the result with the method and worked explanation below.

The method, explained

Equivalent resistance = R1R2/(R1 + R2).

A WORKED EXAMPLE

Using first resistance = 100 Ω, second resistance = 200 Ω, the result is 66.6666667 Ω. Change these example inputs to match your task; use the method above to check each step.

What to keep in mind

Ideal-component calculation for study and estimation. It does not select safe wiring, protective devices or component ratings for an installation.

Methodology maintained by ClarityKit. How these tools are built and checked.